I think the 3 second rule accurate. So at 100 km/hr, you travel 100,000 metres in an hour, 1667 metres in a minute or 28 metres a second. So if you apply the 3second rule, would need 84 metres of separation between cars travelling at 100 km/hr
With that distance, 3 cars would pull in between!
Still 28 meters is a very long vehicle ,size of a semi trailer truck perhaps.
Funny how every body is talking about that 3 sec rule as if they never drove in the real world.
Try to do that and you'll have 3-4 cars trying to squeeze in between. I've seen situations where the gap between cars was so tight that a compact car would have problem to fit in and yet some jerk forced his way in.
People are what they are for good or bed . In mu opinion police should increase their presence and enforce road rules. In Europe you get ticketed for not having working lights or to dirty vehicle. Not only that ,they also will not let you drive it until vehicle is fixed and inspected. Unfortunately this is not the priority of our law enforcement ,only occasionally.
On the positive side the new vehicles there are systems introduced such as active cruise control that will mitigate if not prevent such accidents.